Table 1.

DTI indices using ROI analysis of selected slices and mid-50% medial gastrocnemius (MG) and lateral gastrocnemius (LG) muscle volumes for young (Y) and senior (S) subjects.

		Medial gastrocnemius			Lateral gastrocnemius
		Young (Y)	Senior (S)	%4	Young (Y)	Senior (S)	%
FA1	tot2	0.2340 ± 0.0207	0.2380 ± 0.0444	1.7	0.2520 ± 0.0311	0.2840 ± 0.0783	12.7
	253	0.1850 ± 0.0173	0.2420 ± 0.1085	30.8	0.1967 ± 0.0751	0.1575 ± 0.0236	−19.9
	503	0.2580 ± 0.0610	0.2200 ± 0.0707	−14.7	0.2000 ± 0.0283	0.2620 ± 0.0396	31
	753	0.2640 ± 0.0336	0.2300 ± 0.0455	−12.9	0.2367 ± 0.0513	0.2200 ± 0.0600	−7.1
λ 1 5	tot	0.0018 ± 0.0001	0.0020 ± 0.0001	11.1*	0.0018 ± 0.0001	0.0020 ± 0.0001	11.1*
	25	0.0014 ± 0.0006	0.0018 ± 0.0005	28.6	0.0013 ± 0.0005	0.0014 ± 0.0005	7.7
	50	0.0018 ± 0.0002	0.0020 ± 0.0003	11.1	0.0021 ± 0.0003	0.0020 ± 0.0010	−4.8
	75	0.0017 ± 0.0002	0.0019 ± 0.0001	11.8	0.0020 ± 0.0003	0.0017 ± 0.0009	−15
λ 2 5	tot	0.0013 ± 0.0001	0.0014 ± 0.0001	7.7*	0.0013 ± 0.0001	0.0014 ± 0.0001	7.7*
	25	0.0012 ± 0.0005	0.0015 ± 0.0005	25.0	0.0011 ± 0.0005	0.0013 ± 0.0005	18.2
	50	0.0013 ± 0.0002	0.0015 ± 0.0003	15.4	0.0016 ± 0.0001	0.0015 ± 0.0007	−6.3
	75	0.0012 ± 0.0002	0.0014 ± 0.0002	16.7	0.0014 ± 0.0001	0.0012 ± 0.0007	−14.3
λ 3 5	tot	0.0011 ± 0.0001	0.0013 ± 0.0001	18.2*	0.0011 ± 0.0001	0.0012 ± 0.0002	9.1*
	25	0.0010 ± 0.0004	0.0011 ± 0.0004	10.0	0.0010 ± 0.0005	0.0010 ± 0.0003	0
	50	0.0011 ± 0.0002	0.0013 ± 0.0003	18.2	0.0014 ± 0.0001	0.0012 ± 0.0006	−14.3
	75	0.0011 ± 0.0002	0.0012 ± 0.0002	9.1	0.0013 ± 0.0002	0.0010 ± 0.0006	−23.1

¹FA: fractional anisotropy, unitless (range: 0-1)

²tot: mid- 50% (from 25% to 75%) medial gastrocnemius muscle voxels

³25, 50, 75: muscle voxels at anatomical location 25%, 50% and 75% from the muscle origin.

⁴% is change calculated with respect to the young group

⁵Eigenvalues λ1, λ2, λ3 are in units of mm²/sec.

^*significant at p<0.05; two-tailed t-test for independent samples (young-senior age groups)